JP4157837B2 - DRIVE DEVICE, ITS ADJUSTING METHOD, AND IMAGE FORMING DEVICE - Google Patents

Description

  The present invention relates to a drive device that is required to drive a plurality of gears with a single drive unit with high accuracy. For example, the present invention is applied to a drive device for an image carrier in a color image forming apparatus including a plurality of image carriers. Is possible.

JP 2001-188395 A

  In recent years, image forming apparatuses such as copiers, facsimiles, and printers have been required to be full color and to improve printing speed. For this reason, various proposals have been made for a system in which a plurality of image forming units are provided, and color images formed by the respective image forming units are sequentially transferred onto a recording medium held on a conveyance belt or an intermediate transfer belt to obtain a color image.・ It is realized.

  In such a type of color image forming apparatus, color images (positional errors) are generated and the image quality is deteriorated unless the respective color images are accurately superimposed. In Patent Document 1, in a color image forming apparatus including a plurality of photosensitive drums, a color image is formed by detecting the phase of eccentricity of each photosensitive drum and adjusting the timing of image writing to prevent color misregistration. A forming apparatus is disclosed.

  However, the one described in Patent Document 1 has a configuration in which a plurality of photosensitive drums are driven by different motors, and includes a detecting means for detecting a driving current of each motor.

  On the other hand, there is an apparatus configured to drive a plurality of photosensitive drums with a single motor for the purpose of cost reduction, but the invention described in Patent Document 1 cannot be applied to such an apparatus. There was a problem.

  The present invention solves the above-described problems in the prior art and can be applied to an image forming apparatus configured to drive a plurality of image carriers with a single driving unit. In this case, the occurrence of color misregistration can be reduced with a simple configuration. It is an object of the present invention to provide a driving device that can be prevented from cost.

  According to the present invention, there is provided a driving device in which a plurality of driven gears are meshed with a driving gear mounted on a driving shaft of a motor, and the current fluctuation range of the motor is maximum or minimum in the driving device that drives the driven gear. This is solved by adjusting the meshing of the driven gear with the driving gear so that the phase shift due to the eccentricity of the driven gear is synchronized.

  In order to solve the above-mentioned problem, the present invention provides drive transmission contact / separation means for contacting / separating transmission of driving force to / from a shaft of one of the plurality of driven gears. It is proposed that the drive transmission contact / separation means release the drive transmission for a predetermined time so that the detected drive current of the motor becomes a predetermined value.

  Further, according to the present invention, there is provided an adjustment method of a driving device that meshes a plurality of driven gears with a driving gear mounted on a driving shaft of a motor and drives the driven gear. The problem is solved by shifting the phase by a predetermined angle and assembling the drive gear, adjusting the current fluctuation range of the motor to be maximum or minimum, and synchronizing the phase shift due to the eccentricity of the driven gear.

  Further, according to the present invention, there is provided an adjustment method of a driving device that meshes a plurality of driven gears with a driving gear mounted on a driving shaft of a motor and drives the driven gears. Drive transmission contact / separation means for connecting / separating drive force to / from one gear shaft of the gear is provided, the drive current of the motor is detected and fed back, and the drive current detection value of the motor becomes a predetermined value. As described above, the drive transmission contact / separation means releases the drive transmission for a predetermined time, and the phase shift due to the eccentricity of the driven gear is synchronized.

  Further, according to the present invention, there is provided a method for adjusting a plurality of driven gears to a driving gear mounted on a driving shaft of a motor and adjusting the driving device for driving the driven gear. More than a certain number of driven gears, the prepared driven gears are individually engaged with the driving gears, and the current fluctuation widths of the motors are sequentially detected, and the driven gears close to the detected current fluctuation widths are prepared. The problem is solved by assembling the gears to the drive gear.

  Further, according to the present invention, a plurality of photosensitive drums are arranged side by side, and a visible image formed on the plurality of photosensitive drums is transferred onto a recording medium directly or via an intermediate transfer member. In the image forming apparatus for forming a color image, the distance between the plurality of photosensitive drums is set to an integral multiple of the drum circumference, and the current value of the motor that drives at least two of the photosensitive drums is detected. And adjusting the meshing of the drum gears of the at least two photosensitive drums engaged with the driving gear mounted on the driving shaft of the motor so that the fluctuation range of the motor driving current is maximized. This is solved by synchronizing the phase shift due to the eccentricity of the drum gear of the body.

  Further, according to the present invention, a plurality of photosensitive drums are arranged side by side, and a visible image formed on the plurality of photosensitive drums is transferred onto a recording medium directly or via an intermediate transfer member. In the image forming apparatus for forming a color image, the distance between the plurality of photosensitive drums is set to [integer +1/2] times the drum circumferential length, and at least two motors for driving the photosensitive drums are set. Detecting the current value, and adjusting the meshing of the drum gears of the at least two photosensitive drums meshed with the driving gear mounted on the driving shaft of the motor so that the fluctuation range of the motor driving current is minimized; This is solved by synchronizing the phase shift caused by the eccentricity of the drum gears of the at least two photosensitive members.

  In order to solve the above-described problem, the present invention provides drive transmission contact / separation means for contacting / separating transmission of driving force to / from a shaft of one of the at least two photosensitive drums, and the motor It is proposed that the drive transmission contact / separation means be released for a predetermined time so that the drive current detection value of the motor is detected and fed back, and the drive current detection value of the motor becomes a predetermined value.

  According to the drive device of the first aspect, the phase shift due to the eccentricity of the driven gear can be synchronized by adjusting the meshing of the driven gear based on the fluctuation range of the driving current of the motor that drives the rotating body. Therefore, a plurality of driven gears can be driven with high accuracy.

With the configuration of the second aspect, the adjustment can be automated.
According to the adjustment method of the third aspect, the phase of the driven gear is shifted by a predetermined angle and assembled to the driving gear, and the eccentricity of the driven gear is adjusted by adjusting the motor current fluctuation range to be maximum or minimum. It is possible to synchronize the phase shift due to the above, and the drive device can be adjusted accurately at low cost.

  According to the adjustment method of the fourth aspect, by detecting and feeding back the driving current of the motor, the driving transmission contacting / separating means is released for a predetermined time so that the driving current becomes a predetermined value. It becomes possible to synchronize the phase shift due to the eccentricity of the driven gear, and the drive device adjustment can be automated.

  According to the adjustment method of the fifth aspect, the eccentric amounts of the plurality of driven gears can be made uniform based on the driving current of the motor. There is no need, and adjustment work can be performed easily.

  According to the image forming apparatus of the sixth aspect, it is possible to synchronize the phase shift due to the eccentricity of the drum gear in the plurality of photosensitive drums in which the distance between the drums is set to an integral multiple of the drum circumferential length. Color offset can be prevented by offsetting the minutes.

  According to the image forming apparatus of the seventh aspect, it is possible to synchronize the phase shift due to the eccentricity of the drum gear in the plurality of photosensitive drums in which the distance between the drums is set to [integer +1/2] times the drum circumference. Therefore, the color shift can be prevented by offsetting the phase shift due to the eccentricity.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional configuration diagram showing an outline of a color printer which is an example of an image forming apparatus according to the present invention. The color printer 1 has a configuration in which a paper feeding unit 2 is arranged at the lower part of the apparatus main body and an image forming unit 3 is arranged above the paper feeding unit 2. The image forming unit 3 is provided with an intermediate transfer belt 6 composed of a flexible endless belt wound around driven and drive rollers 4 and 5. Four image forming units 10 are disposed along the lower running side of the intermediate transfer belt 6.

  Each image forming unit 10 includes a photosensitive drum 11 as an image carrier in contact with the intermediate transfer belt 6. Around the photosensitive drum 11, a charging roller 12, a developing device 13, a cleaning unit 14, and the like are disposed. Further, a primary transfer unit is disposed inside the intermediate transfer belt 6 at a position where the photosensitive drum 11 is in contact with the intermediate transfer belt 6. The transfer roller 15 is provided. In this example, the four image forming units 10 have the same structure, but the developer colors handled by the developing device 13 of each image forming unit are different in four colors, magenta, cyan, yellow, and black. Yes. In the case of this example, the four image forming units 10 are arranged in the order of magenta, cyan, yellow, and black from the left in the figure, and M, C, Y, Bk representing each color in the photosensitive drum 11. Is written.

  An optical writing device 7 is provided below the image forming unit 10. The optical writing device 7 includes a polygon mirror 8, a mirror group 9, and the like, and irradiates the surface of the photosensitive drum 11 of each image forming unit with light-modulated laser light. The optical writing device may be provided individually for each image forming unit 8, but using a common optical writing device is advantageous in terms of cost.

  A transfer roller 18 as a secondary transfer unit is provided at a position facing the roller 5 of the intermediate transfer belt 6. A registration roller 17 is provided in front of the secondary transfer position, and a fixing device 19 is provided above the secondary transfer position.

An image forming operation in the color printer 1 will be briefly described.
The photosensitive drum 11 of the image forming unit 10 is rotationally driven in the clockwise direction in the figure by a driving means described later, and the surface of the photosensitive drum 11 is uniformly charged to a predetermined polarity by the charging roller 12. The charged photoconductor surface is irradiated with laser light from the optical writing device 7, whereby an electrostatic latent image is formed on the photoconductor drum 11 surface. At this time, the image information exposed to each photosensitive drum 11 is single-color image information obtained by separating a desired full-color image into color information of yellow, magenta, cyan, and black. Each color toner is applied from the developing device 13 to the electrostatic latent image formed in this manner, and visualized as a toner image.

  Further, the intermediate transfer belt 6 is driven to run counterclockwise in the drawing as indicated by an arrow, and each color toner image is sequentially superimposed on the intermediate transfer belt 6 from the photosensitive drum 11 by the action of the transfer roller 15 in each image forming unit 10. Transcribed. In this way, the intermediate transfer belt 6 carries a full-color toner image on its surface.

  The residual toner adhering to the surface of the photosensitive drum after the toner image is transferred is removed from the surface of the photosensitive drum by the cleaning means 14, and then the surface potential is initialized by the action of the static eliminator. Prepare for the next image formation.

  On the other hand, a transfer material such as paper or an OHP sheet is fed from the paper feeding unit 2 by the feed roller 16. The transfer material is sent out toward the secondary transfer position by the registration roller 17 in a timing with the toner image carried on the intermediate transfer belt 6. In this example, a transfer voltage having a polarity opposite to the toner charging polarity of the toner image on the surface of the intermediate transfer belt is applied to the transfer roller 18, whereby the toner image on the surface of the intermediate transfer belt is collectively transferred onto the transfer material. When the transfer material to which the toner image has been transferred passes through the fixing device 19, the toner image is fused and fixed to the transfer material by heat and pressure. The fixed transfer material is discharged by a paper discharge roller 20 to a paper discharge unit 23 formed on the upper surface of the apparatus main body 1.

  The above description of the operation is an image forming operation when a full-color image is formed on a transfer material. A single-color image is formed by using any one of the image forming units 10, or a two-color or three-color image. Can also be formed. In the case of monochrome printing, image formation is performed using the rightmost Bk unit in the figure among the four image forming units.

  FIG. 2 shows a driving mechanism of the photosensitive drum 11 in the color printer 1 of this example. As described above, the color printer 1 of this example is a quadruple tandem system in which the four image forming units 10 are arranged along one side of the intermediate transfer belt 6. Each image forming unit 10 includes a photoconductor drum 11 and, as shown in FIG. 2, large-diameter gears (hereinafter referred to as drum drive gears) attached to the photoconductor drums for driving the four photoconductor drums 11. 33a-d are arranged in parallel. Each gear is marked with letters M, C, Y, and Bk so that the correspondence with the photosensitive drums of each color can be easily understood.

  In the driving mechanism of the photosensitive drum of this example, a gear 31 (hereinafter referred to as a motor gear) 31 fixed to a driving shaft of a motor 30 as driving means is engaged with drum driving gears 33a and 33b. Accordingly, the two photosensitive drums 11M and 11C (that is, the drum driving gears 33a and 33b) are directly driven from the motor 30. Further, an idler gear 32 that meshes with the drum drive gear 33b and the drum drive gear 33c is provided. As a result, the photosensitive drum 11Y (the drum drive gear 33c) passes from the motor gear 31 of the motor 30 via the drum drive gear 33b and the idler gear 32. Will be driven indirectly. A gear 35 fixed to the drive shaft of the second motor 34 is engaged with the other drum drive gear 33d. That is, the photosensitive drum 11Bk is driven by the second motor 34.

FIG. 3 is a schematic diagram showing the positional relationship between the two photosensitive drums 11M and 11C directly driven by the first motor 30.
As shown in this figure, the distance between the photosensitive drums 11M and 11C is L1, and the diameters of the photosensitive drums are Da and Db, respectively. Further, the linear velocity of each photosensitive drum 11 is VD, and the linear velocity of the intermediate transfer belt 6 is VB. In the printer of this example, the drum diameters of the photosensitive drums are equal, and the distance between the photosensitive drums is a natural number multiple of the drum diameter. The linear velocity of the photosensitive drum 11 and the linear velocity of the intermediate transfer belt 6 are substantially the same, and are regarded as constant velocity here. When these relationships are expressed by an expression,
Da = Db (1)
L1 = n × π × Da (= Db) (2)
However, n is a natural number VD = VB (3)
It becomes.

  Regarding the drum rotation unevenness caused by the eccentricity of the drum drive gears 33a and 33b of the photoconductive drums 11M and 11C, when the relationships (1) to (3) are satisfied, the phase of the rotation unevenness is the same phase. It is more advantageous for “color shift”. This is because each drum rotates exactly n times while the recording paper is conveyed by the distance between the drums (= natural number times the drum diameter). This is because the rotation unevenness component of the drum drive gear 33 is canceled (slip transfer theory).

  That is, as shown in FIG. 4, when the phase of the rotation unevenness of the photoconductor drum 11M and the phase of the rotation unevenness of the photoconductor drum 11C are the same phase, “Isa (= Image start” on the photoconductor drum 11M. The toner image transferred at the timing of “a)” is transferred at “Isb (n = 1, 2, 3)” on the photosensitive drum 11C.

  Here, “matching the rotation unevenness phases of the two drum drive gears” is equivalent to “matching the fluctuation phase of the drive current”. Therefore, as shown on the right side of FIG. 4, the current value for driving the drive motor 30 is detected so that the sum of the rotation unevenness phases of the photosensitive drums 11M and 11C is doubled in amplitude. The meshing of the drum drive gears 33a and 33b with the motor gear 31 may be adjusted so that the current fluctuation range is maximized. As a result, the rotation unevenness phases of the photosensitive drums 11M and 11C can be matched, and the phase shift due to the eccentricity of the drum drive gears 33a and 33b actually assembled can be offset on the intermediate transfer belt 6, and Color shift in the body drums 11M and 11C can be prevented. It should be noted that the detection of the current value of the drive motor 30 and the adjustment of the meshing of the drum drive gear thereby are performed at the printer manufacturing factory.

  A conventional color image forming apparatus, for example, the one described in Patent Document 1 above, includes an individual drive motor for each of the plurality of photosensitive drums, and each drive motor for performing color misregistration prevention control by “phase alignment”. The detection means (in the embodiment, the current detection resistor 126, paragraph 0029, see FIG. 5). Therefore, the cost as the image forming apparatus is increased.

  On the other hand, the color printer of this example has a configuration in which a plurality of photosensitive drums are driven by a single drive motor, and there is no need to install special detection means in the apparatus. Even when color misregistration is prevented by phase matching, an increase in apparatus cost can be suppressed as much as possible, and a high-quality color image forming apparatus can be realized at low cost.

Next, another embodiment of the color printer will be described.
Similar to the color printer described above, the color printer of the second embodiment has an apparatus configuration as shown in FIG. 1, and also has a configuration shown in FIG. 2 as a driving mechanism for each photosensitive drum. It is. Therefore, the description which overlaps is abbreviate | omitted and a different part is demonstrated.

FIG. 5 is a schematic diagram showing the positional relationship between the two photosensitive drums 11M ′ and 11C ′ directly driven by the first motor 30 in the color printer of the second embodiment. As shown in this figure, the distance between the photosensitive drums 11M ′ and 11C ′ is L2, and the diameters of the photosensitive drums are Da ′ and Db ′, respectively. Further, the linear velocity of each photosensitive drum 11 is VD, and the linear velocity of the intermediate transfer belt 6 is VB. In the printer of this example, the drum diameters of the respective photosensitive drums are equal, and the distance between the photosensitive drums is a natural number multiple of the drum diameter +1/2. The linear velocity of the photosensitive drum 11 and the linear velocity of the intermediate transfer belt 6 are substantially the same, and are regarded as constant velocity here. When these relationships are expressed by an expression,
Da '= Db' (4)
L2 = [n + 1/2] × π × Da ′ (= Db ′) (5)
However, n is a natural number VD = VB (3)
It becomes. The condition (3) is the same as in the first embodiment.

  Regarding the drum rotation unevenness caused by the eccentricity of the drum drive gears 33a and 33b (FIG. 2) of the photosensitive drum, the phase of the rotation unevenness is reversed when the relationships (3) to (5) are satisfied. It is more advantageous for “color shift”. This is because, under the conditions of this second embodiment, each recording drum is exactly n times and half while the recording paper is conveyed by the distance between the drums (= natural number times the drum diameter + half cycle). This is because the rotation unevenness component of the drum drive gear 33 is canceled from the viewpoint of the toner on the recording paper because it rotates (slip transfer theory).

  That is, as shown in FIG. 6, when the phase of the rotation unevenness of the photosensitive drum 11M ′ and the phase of the rotation unevenness of the photosensitive drum 11C ′ are opposite to each other, “Isa ′” on the photosensitive drum 11M ′. The toner image transferred at the timing of (= Image start a ′) ”is transferred with“ Isb ′ (n = 1, 2, 3) ”on the photosensitive drum 11C ′. . Here, as shown on the right side of FIG. 6, the sum of the rotation unevenness phases of the photosensitive drums 11M ′ and 11C ′ is theoretically “0 (zero) if the eccentric amounts of the two drum driving gears are the same. As can be seen, the value of the current that drives the drive motor 30 is detected, and the meshing of the drum drive gears 33a and 33b with the motor gear 31 is adjusted so that the current fluctuation width is minimized.

  Thereby, the rotation unevenness phases of the drum drive gears 33a and 33b can be reversed, and the phase shift due to the eccentricity of the drum drive gears 33a and 33b actually assembled can be offset on the intermediate transfer belt 6. Further, it is possible to prevent color misregistration in the photosensitive drums 11M ′ and 11C ′. It should be noted that the detection of the current value of the drive motor 30 and the adjustment of the meshing of the drum drive gear thereby are performed at the printer manufacturing factory.

  Note that adjusting the meshing between the two gears so that the fluctuation range of the drive motor current value in the first and second embodiments is maximized or minimized is the phase shift caused by the eccentricity of the drum drive gears of the two photoconductors. Is to synchronize.

Next, specific meshing adjustments of the drum drive gears 33a and 33b in the first and second embodiments will be described.
As shown in the flowchart of the adjustment procedure in FIG. 7, in the assembly process of the color printer 1, after assembling the gear 31 of the drive motor 30 and the drum drive gears 33a and 33b, the drive motor 30 is driven to generate the current. Detect value. Then, it is determined whether or not the detected drive current value of the motor is as intended, that is, whether or not the maximum value is reached in the case of the first embodiment, and whether or not the minimum value is reached in the case of the second embodiment. To do. If the current value of the drive motor is as intended, the gear meshing optimization is complete. If the current value of the drive motor is not as intended, the gears are shifted and the gears are rearranged to find the optimum value of the motor current (optimum gear meshing).

  In this way, after assembling the gear 31 of the drive motor 30 and the drum drive gears 33a and 33b in the assembly process of the apparatus, the two drum drive gears have an “ideal position (meshing) relationship” due to the motor drive current value. Therefore, the phase shift due to the eccentricity of the drum drive gears 33a and 33b actually assembled can be canceled on the intermediate transfer belt 6, and a high-quality color image with little color shift can be obtained. it can. In addition, since the transmission is driven by gears, the meshing phase does not shift after shipment, and the optimum phase relationship is maintained semi-permanently.

Next, an embodiment in which the gear meshing adjustment is automated will be described.
In this embodiment, although not shown, drive transmission contact / separation means such as a clutch is provided on one of the shafts of the drum drive gear 33a or 33b. Thus, after driving the drive motor for a predetermined time with the drive transmission contact / separation means disconnected, the drive transmission contact / separation means is connected to connect the drum drive gear with the clutch and the other drum drive gear. The relative phase relationship will change. Then, as shown in the flowchart of FIG. 8, the motor 30 is rotated by the gear 31 of the assembled drive motor 30 and the drum drive gears 33a and 33b, and the current value of the drive motor is detected. Then, it is determined whether or not the detected current value is the optimum value, that is, the maximum value in the case of the first embodiment, and the minimum value in the case of the second embodiment. Is cut for a predetermined time to adjust the phase of both drum gears. This is repeated until the detected current value becomes optimum. That is, the detected motor current value is fed back and the clutch is turned off for a predetermined time so as to optimize the detected current value, thereby optimizing the meshing of both drum gears.

  In this embodiment in which the gear meshing adjustment is automated, it is not necessary for the operator to manually change the gear meshing, so that the time required for the optimization work can be greatly reduced. In addition, it is possible to reduce the occurrence of color misregistration due to work errors and current value confirmation errors as much as possible. Furthermore, the automatic adjustment described above can be performed after shipment, and may be performed by a service person at the time of product delivery or maintenance.

  Alternatively, the above automatic adjustment can be programmed so that automatic adjustment of gear meshing optimization can be performed completely automatically, for example, once a week or once a month in the usage state of the product. It is. By performing the gear meshing optimization automatic adjustment at such a predetermined interval, it is possible to suppress the occurrence of color misalignment due to the state change of the drive transmission contact / separation means such as the clutch.

FIG. 9 is a block diagram illustrating the configuration of the control unit of the image forming apparatus according to the present exemplary embodiment.
The drum drive motor 30 is controlled by the CPU 38 via the motor driver 35. The drive transmission contact / separation means 37 is also controlled to contact / separate by a control signal from the CPU 38. The output of the motor current detector 36 is input to the CPU 38. The ROM 39 stores a current value for determining the optimum state of the detected motor current value as a current value table 40. As described above, the output of the motor current detector 36 is compared with the current value table 40 to determine the lowest state, and the contact / separation of the drive transmission contact / separation means 37 is controlled to control the drum drive gears 33a, 33b. Engagement adjustment is performed automatically.

  By the way, when the amount of eccentricity of the drum drive gear directly driven by one drive motor is greatly different, it is conceivable that the color shift is not sufficiently suppressed even if the phase adjustment as described above is performed. Therefore, a plurality of drum drive gears prepared for use as directly driven drum drive gears are assembled one by one (single unit), the drive motor 30 is rotated, and the current fluctuation range is recorded. It is proposed to assemble two gears close to each other as drum drive gears 33a and 33b. In other words, three or more gears are prepared for use as drum drive gears (since there is no choice for two), and two drums are selected from the two that have a close current fluctuation range of the drive motor measured alone. The drive gears 33a and 33b are assembled.

  FIG. 10 is a graph showing fluctuations in the drive current of the motor when the four gears A to D prepared as drum drive gears are driven alone. The current fluctuation ranges of the gears are Ra, Rb, Rc, and Rd, respectively, and the fluctuation ranges are approximately Ra≈Rc and Rb≈Rd. Therefore, when the drum drive gears 33a and 33b are selected from the four gears, it is preferable to assemble the gear A and the gear C as a pair or the gear B and the gear D as a pair. Of course, it is needless to say that two optimal gears (closer to the drive motor current fluctuation range) may be selected and assembled in pairs.

  Thus, since the drive current of the gear alone is measured in advance and the gear eccentricity (= rotation unevenness amplitude) is numerically expressed as “current fluctuation range”, the level of the pair of gears to be combined can be matched. The effect of preventing color misregistration when adjusting the meshing of the drive gear is more effectively exhibited, and a higher quality image can be obtained.

  In addition, it is not necessary to measure the eccentricity of each gear and mark the gears so that the eccentric phase of each gear can be determined as in the past. Thus, it is possible to obtain the maximum effect of suppressing color misregistration (by the meshing adjustment) by phase matching.

  As mentioned above, although this invention was demonstrated by the example of illustration, this invention is not limited to this. For example, the present invention can be applied to a driving device of a color image forming apparatus having three image forming units (for three colors). The black photosensitive drum may be driven by the same drive source (motor) as the other photosensitive drums. The present invention can also be applied to an image forming apparatus that directly superimposes and transfers each color image from a plurality of photosensitive drums onto a recording material to be conveyed. Furthermore, the present invention is not limited to a driving device for a color image forming apparatus, and can be applied to all driving devices that require a plurality of gears to be accurately driven by a single motor.

1 is a cross-sectional configuration diagram illustrating an outline of a color printer which is an example of an image forming apparatus according to the present invention. FIG. 3 is a configuration diagram illustrating a photosensitive drum driving mechanism in the color printer. It is a schematic diagram which shows the positional relationship etc. of two photoconductor drums. It is a graph which shows the phase of the rotation nonuniformity of two photoconductor drums. FIG. 6 is a schematic diagram illustrating a positional relationship between two photosensitive drums in a color printer according to a second embodiment. It is a graph which shows the phase of the rotation nonuniformity of the two photosensitive drums in 2nd Example. It is a flowchart which shows the meshing adjustment procedure of a drum drive gear. It is a flowchart which shows the procedure at the time of automating mesh | engagement adjustment of a drum drive gear. FIG. 3 is a block diagram illustrating a configuration of a control unit of an image forming apparatus that automatically adjusts engagement of a drum drive gear. It is a graph for demonstrating the assembly | attachment of the gears with a near eccentric amount.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Color printer 6 Intermediate transfer belt 10 Image forming unit 11 Photoconductor drum 30 Motor 31 Motor gear 33 Drum drive gear Da, Db Drum diameter Da ', Db' Drum diameter L1, L2 Distance between drums

Claims (8)

In a driving device that engages a plurality of driven gears with a driving gear mounted on a driving shaft of a motor, and drives the driven gear,
A driving device characterized in that the meshing of the driven gear with the driving gear is adjusted so that the current fluctuation width of the motor becomes maximum or minimum, and the phase shift due to the eccentricity of the driven gear is synchronized. Drive transmission contact / separation means for contacting / separating drive force to / from the shaft of one of the plurality of driven gears is provided, and the drive current detected by the motor is detected and fed back. The drive device according to claim 1, wherein the drive transmission contact / separation unit releases the drive transmission for a predetermined time so as to be a predetermined value. In a method of adjusting a driving device that meshes a plurality of driven gears with a driving gear mounted on a driving shaft of a motor and drives the driven gear,
The phase of the driven gear is shifted by a predetermined angle and assembled to the driving gear, the current fluctuation width of the motor is adjusted to be maximum or minimum, and the phase shift due to the eccentricity of the driven gear is synchronized. A method for adjusting the driving device. In a method of adjusting a driving device that meshes a plurality of driven gears with a driving gear mounted on a driving shaft of a motor and drives the driven gear,
Drive transmission contact / separation means for contacting / separating drive force to / from one gear shaft of the plurality of driven gears is provided, and the drive current of the motor is detected and fed back. A method for adjusting a driving device, wherein the drive transmission contact / separation means releases drive transmission for a predetermined time so that a value becomes a predetermined value, and a phase shift due to eccentricity of the driven gear is synchronized. In a method of adjusting a driving device that meshes a plurality of driven gears with a driving gear mounted on a driving shaft of a motor and drives the driven gear,
A number of driven gears greater than or equal to the number to be engaged with the drive gear are prepared, the prepared driven gear is meshed with the drive gear as a single unit, and the current fluctuation width of the motor is sequentially detected, and the detected current fluctuation A method for adjusting a driving device, characterized in that driven gears having a narrow width are assembled to the driving gear. In an image forming apparatus in which a plurality of photosensitive drums are arranged in parallel, and a visible image formed on the plurality of photosensitive drums is transferred onto a recording medium directly or via an intermediate transfer member to form a color image.
The distance between the drums of the plurality of photosensitive drums is set to an integral multiple of the drum circumference, and the current values of the motors that drive at least two of the photosensitive drums are detected, and the fluctuation range of the motor driving current is maximized. The engagement of the drum gears of the at least two photosensitive drums engaged with the drive gear mounted on the drive shaft of the motor is adjusted to synchronize the phase shift due to the eccentricity of the drum gears of the at least two photosensitive members. An image forming apparatus. In an image forming apparatus in which a plurality of photosensitive drums are arranged in parallel, and a visible image formed on the plurality of photosensitive drums is transferred onto a recording medium directly or via an intermediate transfer member to form a color image.
The distance between the drums of the plurality of photosensitive drums is set to [integer +1/2] times the drum circumference, and the current values of the motors that drive at least two of the photosensitive drums are detected. By adjusting the meshing of the drum gears of the at least two photosensitive drums engaged with the driving gear mounted on the driving shaft of the motor so as to minimize the fluctuation range, the eccentricity of the drum gears of the at least two photosensitive drums is adjusted. An image forming apparatus characterized in that phase shift is synchronized. Drive transmission contact / separation means for contacting / separating drive force to / from the shaft of one of the at least two photosensitive drums is provided, and the drive current of the motor is detected and fed back. 8. The image forming apparatus according to claim 6, wherein the drive transmission contact / separation unit releases the drive transmission for a predetermined time so that the detected value becomes a predetermined value.

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